It is generally accepted that preparation for a putt begins with the ability of the golfer to read the character of the green (with regard to slope, speed, grain direction, ball break, etc.) so that a proper putting line can be selected. While somewhat intuitive for a few golfers, this ability is usually developed as a result of practical experience which enables a golfer to develop a useful technique. Even so, it is normal even for many professional golfers to call on the services of their caddy for help in selecting a putting line and a suggestion of required ball speed. This step is so important, many golfers make use of a largely discredited technique called plumb bobbing, i.e. using the putter's shaft as a vertical reference guide. Still, a patent designed in accordance with U.S. Pat. No. 6,358,162 has been found to be United States Golf Association (USGA) conforming. This design provides accurate horizontal and vertical references, and has proven useful in estimating the slope of a green in all directions, especially around the hole, as well as confirming whether the flag pole, trees, fences and fence post references are truly vertical or horizontal.
Once a putting line has been selected, the golfer is faced with the need to impact the ball with enough putter head force for the ball to reach the hole while rolling on the intended putting line, without rolling too far past the hole if it does not drop. It is generally agreed that a repeatable technique is a prime and exquisitely difficult task to achieve, not only for tempo to control distance, but also to maintain putter face orientation to the intended putting line.
Every golfer has individual idiosyncrasies that can introduce variations in the swing path, face orientation and/or timing, so that the same result is not achieved even on repeated attempts to hole a putt of more than a few feet. As a result, putter designers concentrate on incorporating design elements which are either passive or active to compensate for these idiosyncrasies. In general, on almost all putts, golfers try to impact the ball on the putter's sweet spot, with the putter face perpendicular to the intended putting line. Passive elements include features which provide better ball aiming and alignment guides. In addition, incorporating a high moment of inertia passively reduces the magnitude of skewing of the putter face when the putter does not impact the ball on the putter's sweet spot. Active design elements include features such as elastomeric face inserts on the face of the putter where the ball is impacted, the flexing of which increases the dwell time of the ball on the putter face. This is intended to provide the putter face more time to square up to the putting line on impacts which miss the sweet spot and also to enhance feel.
All of these techniques result in various degrees of forgiveness and are regularly sought after by golfers at all levels of proficiency, since the saving of a single stroke can result in a score reduction of as much as 1.5% or more by a professional golfer, and as much as 1% by those less skilled. Since an 18 hole round of golf at par allows 36 strokes, it is easy to see how improvement in this single aspect of the game is so important.